He needed glory and he needed cash. The quickest route to glory was beating up barbarians; stealing their wealth and selling their bodies into slavery got him the cash.
The above is from a stomach-penetrating piece on the life of Julius Caesar (and not Boris Johnson). I do not know whether it is an effect of age, but perhaps the more one is aware of dying —with or without dignity— the more I find such descriptions, such as the one below, are hard to let go of when you close you eyes with the hope that they might open again.
Unlike most ancient swords, the legionary shortsword, or gladius Hispaniensis, was designed for stabbing, not slashing. While longswords and sabres create horrific, often deadly wounds, even an inch of steel can deliver a lethal puncture – especially given the limits of ancient medicine. Yet as combat instructors know, stabbing another human being at close quarters is much harder than cutting them: we have a psychological block against penetrating others’ bodies in that way, a visceral aversion that must be overcome by stern, psychologically brutalising discipline. Roman legionaries were taught to hurl their spears at the enemy line, then advance with shields held close, plunging their gladii in and out of the men arrayed against them. Units that could stomach this gruelling work against heavily armoured fellow citizens were simply killing machines against the less disciplined and lightly armoured Gauls [emphasis added]